Coating agents having high scratch resistance and weathering stability

ABSTRACT

Disclosed are coating compositions comprising (a) at least one hydroxyl-containing compound (A), (b) at least one compound (B) having isocyanate groups, and (c) at least one catalyst (D) for the crosslinking of silane groups, said catalyst (D) comprising phosphorus. It is an aspect of the disclosed coating compositions that (i) one or more constituents of the coating composition contain hydrolyzable silane groups and (ii) the coating composition can be finally cured to a coating which has statistically distributed regions of an Si—O—Si network.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Divisional application of Ser. No. 12/519,458filed on 29 Oct. 2009, which is a National Phase application of PatentApplication PCT/EP2007/011190 filed on 19 Dec. 2007, which claimspriority to DE 10 2006 059 951.9, filed 19 Dec. 2006, all of which arehereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to thermally curable coating compositions,based on aprotic solvents and comprising polyols and polyisocyanateswith hydrolyzable silane groups which lead to coatings which combine ahigh scratch resistance with high gloss and high weathering stability.

BACKGROUND OF THE INVENTION

WO-A-01/98393 describes 2K (2-component) coating compositions comprisinga polyol binder component and a polyisocyanate crosslinker componentpartly functionalized with alkoxysilyl groups. These coatingcompositions are used as primers and are optimized for adhesion tometallic substrates, especially aluminum substrates. Over these coatingcompositions, as part of an OEM finish or a refinish, it is possible toapply basecoat/clearcoat systems. In terms of scratch resistance andweathering stability, the coating compositions of WO 01/98393 are notoptimized.

EP-A-0 994 117 describes moisture-curable mixtures comprising a polyolcomponent and a polyisocyanate component which may partly have beenreacted with a monoalkoxysilylalkylamine that has undergone reactionpreferably to an aspartate. Although coatings formed from such mixturesdo have a certain hardness, they are nevertheless of only limitedsuitability for OEM applications in terms of their weathering stabilityand, in particular, their scratch resistance.

US-A-2006/0217472 describes coating compositions which can comprise ahydroxy-functional acrylate, a low molecular mass polyol component, apolyisocyanate, and an amino-functional alkoxysilyl component,preferably bisalkoxysilylamine. Such coating compositions are used asclearcoat material in basecoat/clearcoat systems and lead toscratchproof coatings. Coating compositions of this kind, however, haveonly very limited storage qualities, and the resulting coatings have lowweathering stability, particularly with respect to UV radiation in awet/dry cycle.

WO 2006/042585 describes clearcoat materials which are suitable for OEMfinishing and which as their main binder component comprisepolyisocyanates whose isocyanate groups, preferably to an extent of morethan 90 mol %, have undergone reaction with bisalkoxysilylamines.Clearcoat materials of this kind combine excellent scratch resistancewith high chemical and weathering resistance. But there is still a needfor a further improvement in the weathering stability, particularly withrespect to cracking under UV irradiation in a wet/dry cycle, withretention of the high level of scratchproofing.

EP-A-1 273 640 describes 2K coating compositions composed of a polyolcomponent and of a crosslinker component consisting of aliphatic and/orcycloaliphatic polyisocyanates, 0.1 to 95 mol % of the free isocyanategroups originally present having undergone reaction withbisalkoxysilylamine. These coating compositions can be used for OEMfinishing and, after their curing is complete, combine good scratchresistance with effective resistance to environmental influences.Nevertheless, these coating compositions have a particularly strongpropensity toward aftercrosslinking, which—straight after the finalthermal curing only results in inadequate scratch resistance of thecoatings. The strong post-crosslinking likewise has a negative impact onthe weathering stability since it leads to an increased risk of crackingunder pressure.

The as yet unpublished German patent application P102007013242 describescoating compositions which comprise surface-actively modified,silane-containing compounds. These coating compositions lead to finallycured coatings which have a higher density of Si atoms of the Si—O—Sinetwork in the near-surface coating zone—owing to the accumulation ofthe surface-actively modified, silane-containing compounds prior tothermal curing—than in the bulk. This accumulation of the Si—O—Sinetwork at the surface is specifically not exhibited by the coatings ofthe invention; instead, the regions of the Si—O—Si network of thefinally cured coating of the invention are distributed statistically.

It was an object of the present invention to provide coatingcompositions, particularly for the clearcoat film in OEM finishes andautomotive refinishes, that lead to a network with a high degree ofweathering stability, the unwanted formation of moieties unstable tohydrolysis and weathering being very largely suppressed, in order toensure high acid resistance. In addition, the coating compositions oughtto lead to coatings which already have a high degree of scratchproofingstraight after thermal curing and in particular a high retention ofgloss after scratch exposure. Moreover, the coatings and coatingsystems, especially the clearcoat systems, ought to be able to beproduced even in film thicknesses >40 μm without stress cracksoccurring. This is a key requirement for the use of the coatings andcoating systems, particularly of the clearcoat systems, in thetechnologically and esthetically particularly demanding field ofautomotive OEM finishing.

The intention in particular was to provide clearcoat systems featuringhigh resistance, particularly to cracking, under weathering with UVradiation in a wet/dry cycle, in combination with outstanding scratchproofing.

Furthermore, the new coating compositions ought to be preparable easilyand with very good reproducibility, and ought not to present anyenvironmental problems during application of the coating material.

SUMMARY

In the light of the above objectives, coating compositions have beenfound comprising

-   (a) at least one hydroxyl-containing compound (A),-   (b) at least one compound (B) having free and/or blocked isocyanate    groups,-   (c) at least one catalyst (D) for the crosslinking of silane groups,    where-   (i) one or more constituents of the coating composition contain    hydrolyzable silane groups and-   (ii) the coating composition can be finally cured to a coating which    has statistically distributed regions of an Si—O—Si network,    wherein the catalyst (D) or the catalysts (D) is or are    phosphorus-containing.

In light of the prior art it was surprising and unforeseeable for theskilled worker that the objects on which the present invention was basedcould be achieved by means of the coating composition of the invention.

The components of the invention can be prepared particularly easily andwith very good reproducibility, and do not cause any significanttoxicological or environmental problems during application of thecoating material.

The coating compositions of the invention produce new coatings andcoating systems, especially clearcoat systems, which are highlyscratchproof and, in contrast to common, highly crosslinked scratchproofsystems, are acid-resistant. Moreover, the coatings and coating systemsof the invention, especially the clearcoat systems, can be produced evenin film thicknesses >40 μm without stress cracks occurring. Consequentlythe coatings and coating systems of the invention, especially theclearcoat systems, can be used in the technologically and estheticallyparticularly demanding field of automotive OEM finishing. In thatcontext they are distinguished by particularly high carwash resistanceand scratchproofing. In particular, the high scratch resistance of thecoatings straight after the final curing of the coatings is given insuch a way that the coatings can be handled without any problemsstraight after the final curing has finished. Moreover, the resistanceof the coatings of the invention to cracking under UV radiation andwet/dry cycling in the CAM180 test (to DIN EN ISO 11341 February 98 andDIN EN ISO 4892-2 November 00) in combination with a high scratchresistance, is outstanding.

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

In accordance with the invention it is possible to provide coatingcompositions having the relatively high proportions of silanecrosslinking that are needed for the setting of a very high scratchresistance, but which, owing to the deliberate selection of thecatalysts (D) for the silane crosslinking, do not have the disadvantagestypically associated with high proportions of silane crosslinking. Moreparticularly, through the specific selection of the catalyst (D),success is achieved in providing coating compositions which exhibit goodresistance of the coatings of the invention to cracking under UVradiation and wet/dry cycling in the CAM180 test (to DIN EN ISO 11341February 98 and DIN EN ISO 4892-2 November 00) in combination with ahigh scratch resistance, a high gloss, and a high gloss retention afterweathering.

The Catalyst (D) for the Crosslinking of the Silane Groups

It is essential to the invention that use be made as catalyst (D) ofphosphorus-containing, more particularly phosphorus- andnitrogen-containing catalysts. In this context it is also possible touse mixtures of two or more different catalysts (D).

Examples of suitable phosphorus-containing catalysts (D) are substitutedphosphonic diesters and diphosphonic diesters, preferably from the groupconsisting of acyclic phosphonic diesters, cyclic phosphonic diesters,acyclic diphosphonic diesters, and cyclic diphosphonic diesters.

Thus, for example, it is possible to use acyclic phosphonic diesters ofthe general formula (V)

R₁₀—O

P(O)H  (V)

R₁₁—O

or cyclic phosphonic diesters of the general formula (VI)

R₁₀—O

L′P(O)H  (VI)

R₁₁—O.

In the general formulae (V) and (VI) the radicals R₁₀ and R₁₁ are alikeor different from one another; preferably they are alike, and have thedefinition indicated later on below for formula (IV).

In the general formula (VI) the variable L′ stands for

-   -   a covalent bond between an atom of the radical R₁₀ and an atom        of the radical R₁₁;    -   a divalent linking group selected from the group consisting of        oxygen atom, substituted sulfur atom, substituted more        particularly by oxygen, and unsubstituted sulfur atom,        substituted nitrogen atom, substituted more particularly by        alkyl, substituted phosphorus atom, substituted more        particularly by oxygen, and substituted silicon atom,        substituted more particularly by alkyl and alkoxy—more        particularly, oxygen atom; or    -   a divalent linking group selected from the group consisting of        substituted and unsubstituted alkyl containing at least one        heteroatom selected from the group consisting of oxygen atom,        sulfur atom, nitrogen atom, phosphorus atom, and silicon atom,        more particularly oxygen atom, sulfur atom, and nitrogen atom,        or heteroatom-free alkyl having 1 to 10, preferably 1 to 6, and        more particularly 1 to 4 carbon atoms, cycloalkyl having 3 to        10, preferably 3 to 6, and more particularly 6 carbon atoms, and        aryl having 5 to 10 and more particularly 6 carbon atoms.

Furthermore it is also possible, for example, to use acyclicdiphosphonic diesters (D) of the general formula (VII):

(R₁₀—O)(O)PH—O—PH(O)(O—R₁₁)  (VII);

in which the variables have the definition indicated above.

Catalysts of this kind are described for example in the German patentapplication DE-A-102005045228.

Use is made more particularly as catalyst, however, of substitutedphosphoric monoesters and phosphoric diesters, preferably from the groupconsisting of acyclic phosphoric diesters and cyclic phosphoricdiesters, more preferably amine adducts of the phosphoric monoesters anddiesters. The acyclic phosphoric diesters (D) are selected moreparticularly from the group consisting of acyclic phosphoric diesters(D) of the general formula (IV):

R₁₀—O

P(O)OH  (IV);

R₁₁—O

where the radicals R₁₀ and R₁₁ are selected from the group consistingof:

-   -   substituted and unsubstituted alkyl- having 1 to 20, preferably        2 to 16, and more particularly 2 to 10 carbon atoms, cycloalkyl-        having 3 to 20, preferably 3 to 16, and more particularly 3 to        10 carbon atoms, and aryl- having 5 to 20, preferably 6 to 14,        and more particularly 6 to 10 carbon atoms,    -   substituted and unsubstituted alkylaryl-, arylalkyl-,        alkylcycloalkyl-, cycloalkylalkyl-, arylcycloalkyl-,        cycloalkylaryl-, alkylcycloalkylaryl-, alkylarylcycloalkyl-,        arylcycloalkylalkyl-, arylalkylcycloalkyl-,        cycloalkylalkylaryl-, and cycloalkylarylalkyl-, the alkyl,        cycloalkyl-, and aryl groups present therein in each case        containing the above-recited number of carbon atoms; and    -   substituted and unsubstituted radical- of the above-recited        kind, containing at least one, more particularly one, heteroatom        selected from the group consisting of oxygen atom, sulfur atom,        nitrogen atom, phosphorus atom, and silicon atom, more        particularly oxygen atom, sulfur atom, and nitrogen atom and        additionally also being able to represent hydrogen (partial        esterification).

Very particular preference is given to using as catalyst (D) thecorresponding amine-blocked phosphoric esters, and more particularlyamine-blocked phosphoric acid ethylhexyl esters and amine-blockedphosphoric acid phenyl esters, with very particular preferenceamine-blocked bis(2-ethylhexyl) phosphate.

Examples of amines with which the phosphoric esters are blocked are moreparticularly tertiary amines, an example being triethylamine. Particularpreference is given to blocking the phosphoric esters using tertiaryamines which ensure good activity of the catalyst under the curingconditions of 140° C.

Certain amine-blocked phosphoric acid catalysts are also availablecommercially (e.g., Nacure products from King Industries). As anexample, mention may be made, under the name Nacure 4167 from KingIndustries, of a particularly suitable catalyst based on anamine-blocked phosphoric acid partial ester.

The catalysts are used preferably in fractions of 0.01% to 20% byweight, more preferably in fractions of 0.1% to 10% by weight, based onthe nonvolatile constituents of the coating composition of theinvention. In this context, a relatively low level of activity on thepart of the catalyst can be partially compensated by means ofcorrespondingly higher amounts employed.

The Structural Units Having Hydrolyzable Silane Groups

It is essential to the invention that one or more constituents of thecoating composition contain hydrolyzable silane groups. Thesehydrolyzable silane groups lead to the construction of the Si—O—Sinetwork which is distributed statistically in the finally cured coating.This means that there is no deliberate accumulation or depletion of theSi—O—Si network in certain regions of the coating, hence including noaccumulation in the near-surface coating zone as described in the as yetunpublished German patent application P102007013242.

Particularly suitable in this context are coating compositions whereinone or more constituents of the coating composition at least partlycontain one or more, identical or different structural units of theformula (I)

X—Si—R″xG₃ −x  (I)

whereG=identical or different hydrolyzable groups,

X=organic radical, more particularly linear and/or branched alkylene orcycloalkylene radical having 1 to 20 carbon atoms, very preferablyX=alkylene radical having 1 to 4 carbon atoms,

R″=alkyl, cycloalkyl, aryl, or aralkyl, it being possible for the carbonchain to be interrupted by nonadjacent oxygen, sulfur or NRa groups,with Ra=alkyl, cycloalkyl, aryl or aralkyl, preferably R″=alkyl radical,more particularly having 1 to 6 C atoms,

x=0 to 2, preferably 0 to 1, more preferably x=0.

The structure of these silane radicals affects their reactivity. Withregard to the compatibility and the reactivity of the silanes it ispreferred to use silanes having 3 hydrolyzable groups, i.e., x=0.

The hydrolyzable groups G may be selected from the group of halogens,more particularly chlorine and bromine, from the group of alkoxy groups,from the group of alkylcarbonyl groups, and from the group of acyloxygroups. Particular preference is given to alkoxy groups (OR′).

The respective preferred alkoxy radicals (OR′) may be alike ordifferent; what is critical for the structure of the radicals, however,is to what extent they influence the reactivity of the hydrolyzablesilane groups. Preferably R′ is an alkyl radical, more particularlyhaving 1 to 6 C atoms. Particularly preferred radicals R′ are thosewhich increase the reactivity of the silane groups, i.e., represent goodleaving groups. To this extent, a methoxy radical is preferred over anethoxy radical, which is preferred in turn over a propoxy radical. Withparticular preference therefore R′=ethyl and/or methyl, moreparticularly methyl.

The reactivity of organofunctional silanes can also be significantlyinfluenced, furthermore, through the length of the spacers X betweensilane functionality and organic functional group serving for reactionwith the modifying constituent. As examples of this, mention may be madeof the “alpha” silanes, available from the company Wacker, in whichthere is a methylene group, instead of the propylene group present inthe case of “gamma” silanes, between Si atom and functional group. Toillustrate this it is observed thatmethacryloyloxymethyltrimethoxysilane (“alpha” silane, e.g., commercialproduct GENIOSIL® XL 33 from Wacker) is used in preference overmethacryloyloxypropyltrimethoxysilane (“gamma” silane, e.g., commercialproduct GENIOSIL® GF 31 from Wacker) in order to introduce thehydrolyzable silane groups into the coating composition.

Very generally, spacers which increase the reactivity of the silanes arepreferred over spacers which lower the reactivity of the silanes.

In addition, the functionality of the silanes, as well, has an influenceon the properties of the resulting finally cured coating. Byfunctionality in this context is meant the number of radicals of theformula (I) per molecule. The term monofunctional silane thereforerefers to silanes which per silane molecule in each case introduce oneradical of the formula (I) into the constituent that is to be modified.The term difunctional silane refers to silanes which per silane moleculeintroduce in each case two radicals of the formula (I) into theconstituent.

Particular preference is given, in accordance with the invention, tocoating compositions wherein the constituents have been modified with amixture of a monofunctional silane and a difunctional silane.Difunctional silanes used in this context are more particularly thoseamino-functional disilanes of the formula (IIa) that are described lateron below, and monofunctional silanes used are more particularly thosesilanes of the formula (IIIa) that are described later on below.

Generally speaking, then, for a given silanization content, theweathering resistance of the finally cured coating increases in linewith the proportion of monofunctional silane, but at the same time thereis also a decrease in the scratch resistance. In general, moreover, theweathering resistance of the finally cured coating decreases as theproportion of difunctional silane goes up, but at the same time thescratch resistance increases. In the case of high proportions ofdifunctional silane, therefore, other measures must appropriately betaken to increase the weathering resistance, in order to provide thecoating compositions of the invention. By way of example, the degree ofsilanization overall can be lowered—in other words, in the case of themodification of the polyisocyanate component (B) with a (bis-silyl)amineof the formula (IIa), as described below, the proportion of theisocyanate groups reacted overall with a silane can be chosen to beappropriately low. Moreover, as the degree of silanization goes up(i.e., as the overall proportion of the isocyanate groups reacted withthe compounds (IIa) and (IIIa) goes up) and as the fraction ofdifunctional silane (IIa) goes up, the influence of the catalyst on theproperties of the resulting coating becomes ever greater, with theconsequence that in that case, in particular, amine-blocked phosphoricacid-based catalysts are employed.

Finally, it is also possible for nonfunctional substituents on theorganofunctional silane that is used to introduce the structural units(I) and/or (II) and/or (III) to influence the reactivity of thehydrolyzable silane group. This may be illustrated by way of exampletaking as an example bulky voluminous substituents on the aminefunction, which are able to reduce the reactivity of amine-functionalsilanes. Against this backgroundN-(n-butyl)-3-aminopropyltrimethoxysilane is preferred beforeN-cyclohexyl-3-aminopropyltrimethoxysilane for the introduction of thestructural units (III).

Very generally, the radicals which increase the reactivity of thesilanes are preferred over radicals which lower the reactivity of thesilanes.

The structural units of the formula (I) can be introduced into theconstituents of the coating composition in different ways. A featurecommon to the various ways, however, is that the introduction of thestructural units is accomplished via a reaction between the functionalgroups of the constituents it is intended to modify and complementaryfunctional groups of the silane. By way of example, therefore, variouspossibilities for introducing the structural units (I) into the compound(A) containing hydroxyl groups and, where appropriate, further reactivegroups as well, and/or into the compound (B) containing isocyanategroups, are set out below.

Use is made, more particularly in the context of Michael additions, of,for example, primary aminosilanes, such as 3-aminopropyltriethoxysilane(available for example under the trade name Geniosil® GF 93 from WackerChemie), 3-aminopropyltrimethoxysilane (available for example under thetrade name Geniosil® GF 96 from Wacker Chemie),N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (available for exampleunder the trade name Geniosil® GF 9 and also Geniosil® GF 91 from WackerChemie), N-(2-aminoethyl)-3-aminopropylmethyldimethoxy-silane (availablefor example, under the trade name Geniosil® GF 95 from Wacker Chemie),and the like.

Use is made, more particularly in the context of additions toisocyanate-functional compounds, of, for example, secondaryaminosilanes, such as, for example, bis-(2-trimethoxysilylethyl)amine,bis-(2-triethoxysilyl-ethyl)amine, bis(3-triethoxysilylpropyl)amine(available under the trade name Dynasylan® 1122 from Degussa),bis(3-trimethoxysilylpropyl)-amine (available under the trade nameDynasylan® 1124 from Degussa), bis(4-triethoxysilylbutyl)amine,N-(n-butyl)-3-aminopropyl-trimethoxysilane (available under the tradename Dynasylan® 1189 from Degussa),N-(n-butyl)-3-aminopropyltriethoxysilane,N-cyclohexyl-3-aminopropyltrimethoxysilane (available under the tradename Geniosil® GF 92 from Wacker Chemie),N-cyclohexyl-3-aminopropyltriethoxy-silane,N-cyclohexylaminomethylmethyldiethoxysilane (available from WackerChemie under the trade name Geniosil® XL 924),N-cyclohexyl-aminomethyltriethoxysilane (available from Wacker Chemieunder the trade name Geniosil® XL 926),N-phenylaminomethyltrimethoxysilane (available from Wacker Chemie underthe trade name Geniosil® XL 973), and the like.

Epoxy-functional silanes can be used more particularly for addition tocompounds with carboxylic acid or anhydride functionality. Examples ofsuitable epoxy-functional silanes are3-glycidyloxypropyltrimethoxysilane (available from Degussa under thetrade name Dynasylan® GLYMO), 3-glycidyloxypropyltriethoxysilane(available from Degussa under the trade name Dynasylan® GLYEO), and thelike.

Anhydride-functional silanes can be employed more particularly foraddition to epoxy-functional compounds. An example that may be mentionedof a silane with anhydride functionality is3-(triethoxysilyl)-propylsuccinic anhydride (available from WackerChemie under the trade name Geniosil® GF 20).

Silanes of this kind can be used in the context of Michael reactions orelse in the context of metal-catalyzed reactions. Those exemplified are3-methacryloyloxypropyltrimethoxysilane (available for example fromDegussa under the trade name Dynasilan® MEMO, or from Wacker Chemieunder the trade name Geniosil® GF 31),3-methacryloyloxy-propyltriethoxysilane, vinyltrimethoxysilane(available, among others, from Wacker Chemie under the trade nameGeniosil® XL 10), vinyl-dimethoxymethylsilane (available from, amongothers, Wacker Chemie under the trade name Geniosil® XL 12),vinyltriethoxysilane (available, among others, from Wacker Chemie underthe trade name Geniosil® GF 56),(methacryloyloxymethyl)methyldimethoxysilane (available, among others,from Wacker Chemie under the trade name Geniosil® XL 32),methacryloyloxymethyltrimethoxysilane (available, among others, fromWacker Chemie under the trade name Geniosil® XL 33),(methacryloyloxymethyl)methyldiethoxysilane (available, among others,from Wacker Chemie under the trade name Geniosil® XL 34),meth-acryloyloxymethyltriethoxysilane (available, among others, fromWacker Chemie under the trade name Geniosil® XL 36).

Silanes with isocyanato function or carbamate function are employed inparticular in the context of reactions with hydroxy-functionalcompounds. Examples of silanes with isocyanato function are described inWO 07/03857, for example.

Examples of suitable isocyanatoalkyltrialkoxysilanes areisocyanato-propyltrimethoxysilane,isocyanatopropylmethyldimethoxysilane,isocyanatopropylmethyldiethoxysilane, isocyanatopropyltriethoxysilane,isocyanatopropyltriisopropoxysilane,isocyanatopropylmethyldiiso-propoxysilane,isocyanatoneohexyltrimethoxysilane, isocyanatoneo-hexyldimethoxysilane,isocyanatoneohexyldiethoxysilane, isocyanato-neohexyltriethoxysilane,isocyanatoneohexyltriisopropoxysilane,isocyanatoneohexyldiisopropoxysilane,isocyanatoisoamyltrimethoxy-silane,isocyanatoisoamylmethyldimethoxysilane,isocyanatoisoamyl-methyldiethoxysilane,isocyanatoisoamyltriethoxysilane, isocyanato-isoamyltriisopropoxysilaneand isocyanatoisoamylmethyldiisopropoxy-silane. Many isocyanatoalkyltri-and -di-alkoxysilanes are available commercially, for example, under thedesignation SILQUEST® from OSi Specialties, Inc., a Witco Corporationcompany.

The isocyanatopropylalkoxysilane used preferably has a high degree ofpurity, more particularly of at least 95%, and is preferably free fromadditives, such as transesterification catalysts, which can lead tounwanted side reactions.

Use is made in particular of (isocyanatomethyl)methyldimethoxysilane(available from Wacker-Chemie under the trade name Geniosil® XL 42),3-isocyanatopropyltrimethoxysilane (available from Wacker-Chemie underthe trade name Geniosil® XL 40), and N-dimethoxy(methyl)silylmethylO-methylcarbamate (available from Wacker-Chemie under the trade nameGeniosil® XL 65).

More particular preference is given in accordance with the invention tocoating compositions comprising at least one hydroxyl-containingcompound (A) and at least one isocyanato-containing compound (B),wherein one or more constituents of the coating composition comprise, asadditional functional components, between

2.5 and 97.5 mol %, based on the entirety of structural units (II) and(III), of at least one structural unit of the formula (II)

—N(X—SiR″x(OR′)3−x)n(X′—SiR″y(OR′)3−y)m  (II)

whereR′=hydrogen, alkyl or cycloalkyl, it being possible for the carbon chainto be interrupted by nonadjacent oxygen, sulfur or NRa groups, withRa=alkyl, cycloalkyl, aryl or aralkyl, preferably R′=ethyl and/or methylX,X′=linear and/or branched alkylene or cycloalkylene radical having 1to 20 carbon atoms, preferably X,X′=alkylene radical having 1 to 4carbon atoms, R″=alkyl, cycloalkyl, aryl or aralkyl, it being possiblefor the carbon chain to be interrupted by nonadjacent oxygen, sulfur orNRa groups, with Ra=alkyl, cycloalkyl, aryl or aralkyl, preferablyR″=alkyl radical, in particular having 1 to 6 carbon atoms,

n=0 to 2, m=0 to 2, m+n=2, and x,y=0 to 2,

andbetween 2.5 and 97.5 mol %, based on the entirety of structural units(II) and (III), of at least one structural unit of the formula (III)

—Z—(X—SiR″x(OR′)3−x)  (III),

whereZ=—NH—, —NR—, —O—, withR=alkyl, cycloalkyl, aryl or aralkyl, it being possible for the carbonchain to be interrupted by nonadjacent oxygen, sulfur or NRa groups,with Ra=alkyl, cycloalkyl, aryl or aralkyl,x=0 to 2,X, R′, R″ have the meaning given in formula (II).

Very particular preference is given to coating compositions wherein oneor more constituents of the coating composition contain between 5 and 95mol %, more particularly between 10 and 90 mol %, more preferablybetween 20 and 80 mol %, and especially between 30 and 70 mol %, basedin each case on the entirety of the structural units (II) and (III), ofat least one structural unit of the formula (II), and between 5 and 95mol %, more particularly between 10 and 90 mol %, more preferablybetween 20 and 80 mol %, and especially between 30 and 70 mol %, basedin each case on the entirety of the structural units (II) and (III), ofat least one structural unit of the formula (III).

The Hydroxyl-Containing Compound (A)

As hydroxyl-containing compound (A) it is preferred to use both lowmolecular mass polyols and also oligomeric and/or polymeric polyols.

Low molecular mass polyols used are, for example, diols, such as,preferably, ethylene glycol, neopentyl glycol, 1,2-propanediol,2,2-dimethyl-1,3-propanediol, 1,4-butanediol, 1,3-butanediol,1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,6-hexanediol,1,4-cyclohexanedimethanol, and 1,2-cyclohexanedimethanol, and alsopolyols, such as, preferably, trimethylolethane, trimethylolpropane,trimethylolhexane, 1,2,4-butanetriol, pentaerythritol, anddipentaerythritol.

Low molecular mass polyols of this kind are preferably admixed in minorproportions to the oligomeric and/or polymeric polyol component (A).

The preferred oligomeric and/or polymeric polyols (A) have mass-averagemolecular weights Mw>500 daltons, as measured by means of GPC (gelpermeation chromatography), preferably between 800 and 100 000 daltons,in particular between 1000 and 50 000 daltons. Particularly preferredare polyester polyols, polyurethane polyols, polysiloxane polyols, and,in particular, polyacrylate polyols and/or polymethacrylate polyols, andtheir copolymers, referred to as polyacrylate polyols below. The polyolspreferably have an OH number of 30 to 400 mg KOH/g, in particularbetween 100 and 300 KOH/g. The glass transition temperatures, asmeasured by DSC (differential thermoanalysis), of the polyols arepreferably between −150 and 100° C., more preferably between −120° C.and 80° C.

Suitable polyester polyols are described for example in EP-A-0 994 117and EP-A-1 273 640. Polyurethane polyols are prepared preferably byreacting polyester polyol prepolymers with suitable di- orpolyisocyanates and are described in EP-A-1 273 640, for example.Suitable polysiloxane polyols are described for example inWO-A-01/09260, and the polysiloxane polyols recited therein can beemployed preferably in combination with further polyols, especiallythose having relatively high glass transition temperatures.

The polyacrylate polyols that are very particularly preferred inaccordance with the invention are generally copolymers and preferablyhave mass-average molecular weights Mw of between 1000 and 20 000daltons, in particular between 1500 and 10 000 daltons, in each casemeasured by means of gel permeation chromatography (GPC) as against apolystyrene standard. The glass transition temperature of the copolymersis generally between −100 and 100° C., in particular between −50 and 80°C. (measured by means of DSC measurements). The polyacrylate polyolspreferably have an OH number of 60 to 250 mg KOH/g, in particularbetween 70 and 200 KOH/g, and an acid number of between 0 and 30 mgKOH/g.

The hydroxyl number (OH number) indicates how many mg of potassiumhydroxide are equivalent to the amount of acetic acid bound by 1 g ofsubstance during acetylation. For the determination, the sample isboiled with acetic anhydride-pyridine and the acid formed is titratedwith potassium hydroxide solution (DIN 53240-2). The acid number hereindicates the number of mg of potassium hydroxide consumed inneutralizing 1 g of the respective compound of component (b) (DIN EN ISO2114).

The properties of the finally cured coating can also be influencedthrough the selection of the hydroxyl-containing binders. Generallyspeaking, in fact, as the OH number of component (A) goes up, it ispossible to reduce the degree of silanization, i.e., the amount ofstructural units of the formula (I) and/or (II) and/or (III), which inturn has a positive influence on the weathering resistance of thefinally cured coating.

Hydroxyl-containing monomer units used are preferably hydroxyalkylacrylates and/or hydroxyalkyl methacrylates, such as, in particular,2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropylacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl acrylate,3-hydroxypropyl methacrylate, 3-hydroxybutyl acrylate, 3-hydroxybutylmethacrylate, and, in particular, 4-hydroxybutyl acrylate and/or4-hydroxybutyl methacrylate.

Further monomer units used for the polyacrylate polyols are preferablyalkyl methacrylates and/or alkyl methacrylates, such as, preferably,ethyl acrylate, ethyl methacrylate, propyl acrylate, propylmethacrylate, isopropyl acrylate, isopropyl methacrylate, butylacrylate, butyl methacrylate, isobutyl acrylate, isobutyl methacrylate,tert-butyl acrylate, tert-butyl methacrylate, amyl acrylate, amylmethacrylate, hexyl acrylate, hexyl methacrylate, ethylhexyl acrylate,ethylhexyl methacrylate, 3,3,5-trimethylhexyl acrylate,3,3,5-trimethylhexyl methacrylate, stearyl acrylate, stearylmethacrylate, lauryl acrylate or lauryl methacrylate, cycloalkylacrylates and/or cycloalkyl methacrylates, such as cyclopentyl acrylate,cyclopentyl methacrylate, isobornyl acrylate, isobornyl methacrylate,or, in particular, cyclohexyl acrylate and/or cyclohexyl methacrylate.

Further monomer units which can be used for the polyacrylate polyols arevinylaromatic hydrocarbons, such as vinyltoluene, alpha-methylstyreneor, in particular, styrene, amides or nitriles of acrylic or methacrylicacid, vinyl esters or vinyl ethers, and, in minor amounts, inparticular, acrylic and/or methacrylic acid.

In a further embodiment of the invention the hydroxyl-containingcompound A, as well as the hydroxyl groups, comprises structural unitsof the formula (I) and/or of the formula (II) and/or of the formula(III).

Structural units of the formula (II) can be introduced into the compound(A) by incorporation of monomer units containing such structural units,or by reaction of polyols containing further functional groups with acompound of the formula (IIa)

HN(X—SiR″x(OR′)3−x)n(X′—SiR″y(OR′)3−y)m  (IIa),

where the substituents are as defined above. For the reaction of thepolyol with the compound (IIa), the polyol, correspondingly, has furtherfunctional groups which react with the secondary amino group of thecompound (IIa), such as acid or epoxy groups in particular. Inventivelypreferred compounds (IIa) are bis(2-ethyltrimethoxysilyl)amine,bis(3-propyltrimethoxysilyl)amine, bis(4-butyltrimethoxysilyl)amine,bis(2-ethyltriethoxysilyl)amine, bis(3-propyltriethoxysilyl)amine and/orbis(4-butyltriethoxysilyl)amine. bis(3-Propyltrimethoxysilyl)amine isespecially preferred. Aminosilanes of this kind are available forexample under the trade name DYNASILAN® from DEGUSSA or Silquest® fromOSI.

Monomer units which carry the structural elements (II) are preferablyreaction products of acrylic and/or methacrylic acid or ofepoxy-functional alkyl acrylates and/or methacrylates with theabovementioned compounds (IIa).

Structural units of the formula (III) can be introduced into thecompound (A) by incorporation of monomer units containing suchstructural units or by reaction of polyols containing further functionalgroups with a compound of the formula (IIIa)

H—Z—(X—SiR″x(OR′)3−x)  (IIIa),

where the substituents are as defined above. For the reaction of thepolyol with the compound (IIIa) the polyol, correspondingly, has furtherfunctional groups which react with the functional group —ZH of thecompound (IIIa), such as acid, epoxy or ester groups in particular.Inventively preferred compounds (IIIa) are omega-aminoalkyl- oromega-hydroxyalkyltrialkoxysilanes, such as, preferably,2-aminoethyltrimethoxysilane, 2-aminoethyltriethoxysilane,3-aminopropyltrimethoxy-silane, 3-aminopropyltriethoxysilane,4-aminobutyltrimethoxysilane, 4-aminobutyltriethoxysilane,2-hydroxyethyltrimethoxysilane, 2-hydroxyethyltriethoxysilane,3-hydroxypropyltrimethoxysilane, 3-hydroxypropyltriethoxysilane,4-hydroxybutyltrimethoxysilane, and 4-hydroxybutyltriethoxysilane.Particularly preferred compounds (IIIa) areN-(2-(tri-methoxysilyl)-ethyl)alkylamines,N-(3-(trimethoxysilyl)propyl)alkylamines,N-(4-(trimethoxysilyl)butyl)alkylamines,N-(2-(triethoxysilyl)-ethyl)alkylamines,N-(3-(triethoxysilyl)propyl)alkylamines and/orN-(4-(triethoxysilyl)butyl)alkylamines.N-(3-(Trimethoxysilyl)propyl)butylamine is especially preferred.Aminosilanes of this kind are available for example under the trade nameDYNASILAN® from DEGUSSA or Silquest® from OSI.

Monomer units which carry the structural elements (III) are preferablyreaction products of acrylic and/or methacrylic acid or ofepoxy-functional alkyl acrylates and/or methacrylates, and also, in thecase of hydroxy-functional alkoxysilyl compounds, transesterificationproducts of alkyl acrylates and/or methacrylates, especially with theabovementioned hydroxy- and/or amino-functional alkoxysilyl compounds(IIIa).

The Isocyanato-Containing Compounds (B)

As component (B) the coating compositions of the invention comprise oneor more compounds having free, i.e., nonblocked, and/or blockedisocyanate groups. Preferably the coating compositions of the inventioncomprise compounds (B) having free isocyanate groups. Alternatively theisocyanate groups of the isocyanato-containing compounds B can also beused in blocked form. This is preferably the case when the coatingcompositions of the invention are used as one-component systems.

The di- and/or polyisocyanates which serve as parent structures for theisocyanato-containing compounds (B) used with preference in accordancewith the invention are preferably conventional substituted orunsubstituted aromatic, aliphatic, cycloaliphatic and/or heterocyclicpolyisocyanates. Examples of preferred polyisocyanates are as follows:2,4-toluene diisocyanate, 2,6-toluene diisocyanate, diphenylmethane4,4′-diisocyanate, diphenylmethane 2,4′-diisocyanate, p-phenylenediisocyanate, biphenyl diisocyanates, 3,3′-dimethyl-4,4′-diphenylenediisocyanate, tetramethylene 1,4-diisocyanate, hexamethylene1,6-diisocyanate, 2,2,4-trimethylhexane 1,6-diisocyanate, isophoronediisocyanate, ethylene diisocyanate, 1,12-dodecane diisocyanate,cyclo-butane 1,3-diisocyanate, cyclohexane 1,3-diisocyanate, cyclohexane1,4-diisocyanate, methylcyclohexyl diisocyanates, hexahydrotoluene2,4-diisocyanate, hexahydrotoluene 2,6-diisocyanate, hexahydrophenylene1,3-diisocyanate, hexahydrophenylene 1,4-diisocyanate,perhydrodiphenylmethane 2,4′-diisocyanate, 4,4′-methylenedicyclohexyldiisocyanate (e.g., Desmodur® W from Bayer AG), tetramethylxylyldiisocyanates (e.g., TMXDI® from American Cyanamid), and mixtures of theaforementioned polyisocyanates. Additionally preferred polyisocyanatesare the biuret dimers and the isocyanurate trimers of the aforementioneddiisocyanates.

Particularly preferred polyisocyanates PI are hexamethylene1,6-diisocyanate, isophorone diisocyanate, and4,4′-methylenedicyclohexyl diisocyanate, their biuret dimers and/orisocyanurate trimers.

In a further embodiment of the invention the polyisocyanates arepolyisocyanate prepolymers containing urethane structural units whichare obtained by reacting polyols with a stoichiometric excess ofaforementioned polyisocyanates. Polyisocyanate prepolymers of this kindare described for example in U.S. Pat. No. 4,598,131.

The isocyanato-functional compounds (B) that are especially preferred inaccordance with the invention, functionalized with the structural units(II) and (III), are prepared with preference by reacting theaforementioned di- and/or polyisocyanates with the aforementionedcompounds (IIa) and (IIIa), by reacting

between 2.5 and 90 mol %, preferably 5 to 85 mol %, more preferably 7.5to 80 mol %, of the isocyanate groups in the core polyisocyanatestructure with at least one compound (IIa) andbetween 2.5 and 90 mol %, preferably 5 to 85 mol %, more preferably 7.5to 80 mol %, of the isocyanate groups in the core polyisocyanatestructure with at least one compound (IIIa).

The total fraction of the isocyanate groups reacted with the compounds(IIa) and/or (IIIa) in the polyisocyanate compound (B) is between 5 and95 mol %, preferably between 10 and 90 mol %, more preferably between 15and 85 mol % of the isocyanate groups in the core polyisocyanatestructure. Particularly in the case of a high degree of silanization,i.e., if a high proportion of the isocyanate groups, more particularlyat least 50 mol %, have been reacted with the compounds (IIa)/(IIIa),the isocyanate groups are advantageously reacted with a mixture of thecompounds (IIa) and (IIIa).

Particularly preferred compounds (IIa) arebis(2-ethyltrimethoxysilyl)-amine, bis(3-propyltrimethoxysilyl)amine,bis(4-butyltrimethoxysilyl)-amine, bis(2-ethyltriethoxysilyl)amine,bis(3-propyltriethoxysilyl)amine and/or bis(4-butyltriethoxysilyl)amine.bis(3-Propyltrimethoxysilyl)amine is especially preferred. Aminosilanesof this kind are available for example under the trade name DYNASILAN®from DEGUSSA or Silquest® from OSI.

Preferred compounds (IIIa) are 2-aminoethyltrimethoxysilane,2-amino-ethyltriethoxsilane, 3-aminopropyltrimethoxysilane,3-aminopropyltriethoxysilane, 4-aminobutyltrimethoxysilane,4-aminobutyltriethoxysilane, 2-hydroxyethyltrimethoxysilane,2-hydroxyethyltriethoxysilane, 3-hydroxypropyltrimethoxysilane,3-hydroxypropyltriethoxysilane, 4-hydroxybutyltrimethoxysilane, and4-hydroxybutyltriethoxysilane.

Particularly preferred compounds (IIIa) areN-(2-(trimethoxysilyl)ethyl)-alkylamines,N-(3-(trimethoxysilyl)propyl)alkylamines,N-(4-(trimethoxy-silyl)butyl)alkylamines,N-(2-(triethoxysilyl)ethyl)alkylamines,N-(3-(tri-ethoxysilyl)propyl)alkylamines and/orN-(4-(triethoxysilyl)butyl)alkylamines.N-(3-(Trimethoxysilyl)propyl)butylamine is especially preferred.Aminosilanes of this kind are available for example under the trade nameDYNASILAN® from DEGUSSA or Silquest® from OSI.

Especially preferred isocyanato-containing compounds (B) are reactionproducts of hexamethylene 1,6-diisocyanate and/or isophoronediisocyanate, and/or their isocyanurate trimers, withbis(3-propyltri-methoxysilyl)amine andN-(3-(trimethoxysilyl)propyl)butylamine.

The reaction of the isocyanato-containing compounds (B) with thecompounds (IIa) and (IIIa) takes place preferably in inert gas attemperatures of not more than 100° C., preferably at not more than 60°C.

The free isocyanate groups of the isocyanato-containing compounds B canalso be used in blocked form. This is preferably the case when thecoating compositions of the invention are used as one-component systems.For the purpose of blocking it is possible in principle to use anyblocking agent which can be used for blocking polyisocyanates and whichhas a sufficiently low unblocking temperature. Blocking agents of thiskind are very familiar to the skilled worker. It is preferred to useblocking agents as described in EP-A-0 626 888 and EP-A-0 692 007.

The Combination of Components A and B, and Further Components of theCoating Composition

The weight fraction of hydroxyl-containing compounds A to be employed,based on the weight fraction of the isocyanato-containing compounds B,is dependent on the hydroxy equivalent weight of the polyol and on theequivalent weight of the free isocyanate groups of the polyisocyanate B.

It is preferred that in the coating composition of the invention one ormore constituents comprise between 2.5 to 97.5 mol %, based on the sumof structural units (II) and (III), of at least one structural unit (II)and between 2.5 to 97.5 mol %, based on the sum of structural units (II)and (III), of at least one structural unit (III).

The coating compositions of the invention contain preferably between2.5% and 97.5%, more preferably between 5% and 95%, very preferablybetween 10% and 90%, and in particular between 20% and 80%, by weight,based on the amount of nonvolatile substances in the coatingcomposition, of the hydroxyl-containing compounds (A), and preferablybetween 2.5% and 97.5%, more preferably between 5% and 95%, verypreferably between 10% and 90%, and in particular between 20% and 80%,by weight, based on the amount of nonvolatile substances in the coatingcomposition, of the isocyanato-containing compounds (B).

Based on the sum of the functional groups critical for crosslinking inthe coating composition of the invention, formed from the fractions ofthe hydroxyl and isocyanate groups and also the fractions of thestructural elements (I) or (II) and (III), the structural elements (I)or (II) and (III) are present preferably in fractions of 2.5 to 97.5 mol%, more preferably between 5 and 95 mol %, and very preferably between10 and 90 mol %.

In order to ensure further-improved resistances of the coatings of theinvention to cracking under UV radiation and wet/dry cycling in theCAM180 test (to DIN EN ISO 11341 February 98 and DIN EN ISO 4892-2November 00) in combination with a high scratch resistance directlyfollowing the final thermal cure, a high gloss and a high glossretention after weathering, it is preferred, moreover, to choose theamount of structural units (I) and/or (II) and/or (III) to be not morethan a level such that the coating compositions of the invention containless than 6.5% by mass of Si of structural units (I) and/or (II) and/or(III), very preferably not more than 6.0% by mass of Si of thestructural units (I) and/or (II) and/or (III), based in each case on thesolids content of the coating compositions. This silane content in % bymass of Si is determined arithmetically from the amounts used of thecompounds with the structural unit (I) and the compounds (IIa) and/or(IIIa).

In a further embodiment of the invention the structural elements (I),(II) and/or (III) may additionally also be part of one or more furthercomponents (C), different than the components (A) and (B), in which casethe criteria to be applied are those specified above. By way of exampleit is possible as component (C) to use oligomers or polymers containingalkoxysilyl groups, such as, for example, the poly(meth)acrylatesspecified in patents and patent applications U.S. Pat. No. 4,499,150,U.S. Pat. No. 4,499,151 or EP-A-0 571 073, as carriers of structuralelements (III), or to use the compounds specified in WO-A-2006/042585,as carriers of structural elements (II). Generally speaking, components(C) of this kind are used in fractions of up to 40%, preferably up to30%, more preferably up to 25%, by weight, based on the nonvolatileconstituents of the coating composition.

The weight fractions of the polyol A and of the polyisocyanate B arepreferably selected such that the molar equivalent ratio of theunreacted isocyanate groups of the isocyanate-containing compounds (B)to the hydroxyl groups of the hydroxyl-containing compounds (A) isbetween 0.9:1 and 1:1.1, preferably between 0.95:1 and 1.05:1, morepreferably between 0.98:1 and 1.02:1.

Where the compositions are one-component coating compositions, aselection is made of the isocyanato-containing compounds (B) whose freeisocyanate groups have been blocked with the blocking agents describedabove.

In the case of the inventively preferred 2-component (2K) coatingcompositions, a coating component comprising the hydroxyl-containingcompound (A) and also further components, described below, is mixedconventionally with a further coating component, comprising theisocyanato-containing compound (B) and, where appropriate, further ofthe components described below, this mixing taking place shortly beforethe coating composition is applied; generally speaking, the coatingcomponent that comprises the compound (A) comprises the catalyst andalso part of the solvent.

Solvents suitable for the coating compositions of the invention are inparticular those which, in the coating composition, are chemically inerttoward the compounds (A) and (B) and also do not react with (A) and (B)when the coating composition is being cured. Examples of such solventsare aliphatic and/or aromatic hydrocarbons such as toluene, xylene,solvent naphtha, Solvesso 100 or Hydrosol® (from ARAL), ketones, such asacetone, methyl ethyl ketone or methyl amyl ketone, esters, such asethyl acetate, butyl acetate, pentyl acetate or ethyl ethoxypropionate,ethers, or mixtures of the aforementioned solvents. The aprotic solventsor solvent mixtures preferably have a water content of not more than 1%,more preferably not more than 0.5%, by weight, based on the solvent.

Besides the compounds (A), (B), and (C) it is possible additionally touse further binders (E), which preferably are able to react and formnetwork points with the hydroxyl groups of the compound (A) and/or withthe free isocyanate groups of the compound (B) and/or with thealkoxysilyl groups of the compounds (A), (B) and/or (C).

By way of example it is possible to use amino resins and/or epoxy resinsas component (E). Suitable amino resins are the typical, known aminoresins, some of whose methylol and/or methoxymethyl groups may have beendefunctionalized by means of carbamate or allophanate groups.Crosslinking agents of this kind are described in patents U.S. Pat. No.4,710,542 and EP-B-0 245 700 and also in the article by B. Singh andcoworkers, “Carbamylmethylated Melamines, Novel Crosslinkers for theCoatings Industry” in Advanced Organic Coatings Science and TechnologySeries, 1991, Volume 13, pages 193 to 207.

Generally speaking, such components (E) are used in fractions of up to40%, preferably up to 30%, more preferably up to 25%, by weight, basedon the nonvolatile constituents of the coating composition. The coatingcomposition of the invention may further comprise at least one typical,known coatings additive in effective amounts, i.e. in amounts preferablyup to 30%, more preferably up to 25%, and in particular up to 20% byweight, in each case based on the nonvolatile constituents of thecoating composition.

Examples of suitable coatings additives are:

-   -   particularly UV absorbers;    -   particularly light stabilizers such as HALS compounds,        benzotriazoles or oxalanilides;    -   free-radical scavengers;    -   slip additives;    -   polymerization inhibitors;    -   defoamers;    -   reactive diluents, of the kind which are common knowledge from        the prior art, and which are preferably inert toward the        —Si(OR)3 groups;    -   wetting agents such as siloxanes, fluorine compounds, carboxylic        monoesters, phosphoric esters, polyacrylic acids and their        copolymers, or polyurethanes;    -   adhesion promoters such as tricyclodecanedimethanol;    -   flow control agents;    -   film-forming assistants such as cellulose derivatives;    -   fillers such as, for example, nanoparticles based on silicon        dioxide, aluminum oxide or zirconium oxide; for further details        refer to Römpp Lexikon “Lacke and Druckfarben” Georg Thieme        Verlag, Stuttgart, 1998, pages 250 to 252;    -   rheology control additives, such as the additives known from        patents WO 94/22968, EP-A-0 276 501, EP-A-0 249 201 or WO        97/12945; crosslinked polymeric microparticles, as disclosed for        example in EP-A-0 008 127; inorganic phyllosilicates such as        aluminum-magnesium silicates, sodium-magnesium, and        sodium-magnesium-fluorine-lithium phyllosilicates of the        montmorillonite type; silicas such as Aerosils; or synthetic        polymers containing ionic and/or associative groups such as        polyvinyl alcohol, poly(meth)acrylamide, poly(meth)acrylic acid,        polyvinylpyrrolidone, styrene-maleic anhydride copolymers or        ethylene-maleic anhydride copolymers and their derivatives, or        hydrophobically modified ethoxylated urethanes or polyacrylates;    -   and/or flame retardants.

In a further embodiment of the invention the coating composition of theinvention may additionally comprise further pigments and/or fillers andmay serve for producing pigmented topcoats. The pigments and/or fillersemployed for this purpose are known to the skilled worker.

Because the coatings of the invention produced from the coatingcompositions of the invention adhere excellently even to electrocoats,surfacer coats, basecoat systems or typical, known clearcoat systemsthat have already cured, they are outstandingly suitable not only foruse in automotive OEM finishing but also for automotive refinish or forthe modular scratchproofing of automobile bodies that have already beenpainted.

The coating compositions of the invention can be applied by any of thetypical application methods, such as spraying, knife coating, spreading,pouring, dipping, impregnating, trickling or rolling, for example. Inthe course of such application, the substrate to be coated may itself beat rest, with the application equipment or unit being moved.Alternatively the substrate to be coated, in particular a coil, may bemoved, with the application unit at rest relative to the substrate orbeing moved appropriately.

Preference is given to employing spray application methods, such ascompressed-air spraying, airless spraying, high-speed rotation,electrostatic spray application (ESTA), alone or in conjunction with hotspray application such as hot-air spraying, for example.

The applied coating compositions of the invention can be cured after acertain rest time. The rest time serves, for example, for the levelingand devolatilization of the coating films or for the evaporation ofvolatile constituents such as solvents. The rest time may be assistedand/or shortened by the application of elevated temperatures and/or by areduced humidity, provided this does not entail any damage or alterationto the coating films, such as premature complete crosslinking, forinstance.

The thermal curing of the coating compositions has no peculiarities interms of method but instead takes place in accordance with the typical,known methods such as heating in a forced-air oven or irradiation withIR lamps. The thermal cure may also take place in stages. Anotherpreferred curing method is that of curing with near infrared (NIR)radiation.

The thermal cure takes place advantageously at a temperature of 30 to200° C., more preferably 40 to 190° C., and in particular 50 to 180° C.for a time of 1 min up to 10 h, more preferably 2 min up to 5 h, and inparticular 3 min to 3 h, although longer cure times may be employed inthe case of the temperatures that are employed for automotive refinish,which are preferably between 30 and 90° C.

The coating compositions of the invention produce new cured coatings,especially coating systems, more particularly clearcoat systems;moldings, especially optical moldings; and self-supporting films, all ofwhich are highly scratchproof and in particular are stable to chemicalsand to weathering. The coatings and coating systems of the invention,especially the clearcoat systems, can in particular be produced even infilm thicknesses >40 μm without stress cracks occurring.

For these reasons the coating compositions of the invention are ofexcellent suitability as decorative, protective and/or effect-imparting,highly scratchproof coatings and coating systems on bodies of means oftransport (especially motor vehicles, such as motor cycles, buses,trucks or automobiles) or parts thereof; on buildings, both interior andexterior; on furniture, windows, and doors; on plastics moldings,especially CDs and windows; on small industrial parts, on coils,containers, and packaging; on white goods; on films; on optical,electrical, and mechanical components; and on hollow glassware andarticles of everyday use.

The coating compositions and coating systems of the invention,especially the clearcoat systems, are employed in particular in thetechnologically and esthetically particularly demanding field ofautomotive OEM finishing and also of automotive refinish. Withparticular preference the coating compositions of the invention are usedin multistage coating methods, particularly in methods where a pigmentedbasecoat film is first applied to an uncoated or precoated substrate andthereafter a film with the coating compositions of the invention isapplied.

Not only water-thinnable basecoat materials but also basecoat materialsbased on organic solvents can be used. Suitable basecoat materials aredescribed for example in EP-A-0 692 007 and in the documents cited therein column 3 lines 50 et seq. The applied basecoat material is preferablyfirst dried, i.e., at least some of the organic solvent and/or water isstripped from the basecoat film in an evaporation phase. Drying isaccomplished preferably at temperatures from room temperature to 80° C.Drying is followed by the application of the coating composition of theinvention. Subsequently the two-coat system is baked, preferably underconditions employed for automotive OEM finishing, at temperatures from30 to 200° C., more preferably 40 to 190° C., and in particular 50 to180° C., for a time of 1 min up to 10 h, more preferably 2 min up to 5h, and in particular 3 min to 3 h, although longer cure times may alsobe employed at the temperatures employed for automotive refinish, whichare preferably between 30 and 90° C.

The coats produced with the coating composition of the invention arenotable in particular for an especially high chemical stability andweathering stability and also for a very good carwash resistance andscratchproofing, in particular for an excellent combination ofscratchproofing and weathering stability with respect to UV radiation ina wet/dry cycle.

In a further preferred embodiment of the invention, the coatingcomposition of the invention is used as a transparent clearcoat materialfor coating plastics substrates, especially transparent plasticssubstrates. In this case the coating compositions include UV absorbers,which in terms of amount and type are also designed for effective UVprotection of the plastics substrate. Here as well, the coatingcompositions are notable for an outstanding combination ofscratchproofing and weathering stability with respect to UV radiation ina wet/dry cycle. The plastics substrates thus coated are used preferablyas a substitute for glass components in automobile construction, theplastics substrates being composed preferably of polymethyl methacrylateor polycarbonate.

EXAMPLES Preparation of Inventive Component B Preparation Example B1Preparation of a Partly Silanized Polyisocyanate (HDI with 100 mol % ofIIIa: Conversion c=30 mol %)

A three-neck glass flask equipped with a reflux condenser and athermometer is charged with 57.3 parts by weight of trimerizedhexamethylene diisocyanate (HDI) (Basonat HI 100 from BASF AG) and 88.0parts by weight of solvent naphtha. With reflux cooling, nitrogenblanketing, and stirring, 21.8 parts by weight ofN-[3-(tri-methoxysilyl)propyl]butylamine (IIIa) (Dynasilan® 1189 fromDegussa) are metered in at a rate such that 50 to 60° C. are notexceeded. After the end of the metered addition, the reactiontemperature is held at 50 to 60° C. until the isocyanate mass fractionas determined by titration is at the theoretically calculated 70 mol %.

The solution of the partly silanized polyisocyanate has a solids contentof 47.1% by weight.

Preparation Example B2 Preparation of a Partly Silanized Polyisocyanate(HDI with 70 mol % of IIIa and 30 mol % of IIa: Conversion c=30 mol %)

A three-neck glass flask equipped with a reflux condenser and athermometer is charged with 57.3 parts by weight of trimerizedhexamethylene diisocyanate (HDI) (Basonat HI 100 from BASF AG) and 69.7parts by weight of solvent naphtha. With reflux cooling, nitrogenblanketing, and stirring, a mixture of 14.8 parts by weight ofN-[3-(tri-methoxysilyl)propyl]butylamine (Dynasilan® 1189 from Degussa)(IIIa) and 9.2 parts by weight of bis[3-(trimethoxysilyl)propyl]amine(IIa) (Dynasilan® 1124 from Degussa) is metered in at a rate such that50 to 60° C. are not exceeded. After the end of the metered addition,the reaction temperature is held at 50 to 60° C. until the isocyanatemass fraction as determined by titration is at the theoreticallycalculated 70 mol %.

The solution of the partly silanized polyisocyanate has a solids contentof 53.9% by weight.

Preparation Example B3 Preparation of a Partly Silanized Polyisocyanate(HDI with 30 mol % of IIIa and 70 mol % of IIa: Conversion c=30 mol %)

A three-neck glass flask equipped with a reflux condenser and athermometer is charged with 57.3 parts by weight of trimerizedhexamethylene diisocyanate (HDI) (Basonat HI 100 from BASF AG) and 69.7parts by weight of solvent naphtha. With reflux cooling, nitrogenblanketing, and stirring, a mixture of 6.4 parts by weight ofN-[3-(tri-methoxysilyl)propyl]butylamine (Dynasilan® 1189 from Degussa)(IIIa) and 21.5 parts by weight of bis[3-(trimethoxysilyl)propyl]amine(IIa) (Dynasilan® 1124 from Degussa) is metered in at a rate such that50 to 60° C. are not exceeded. After the end of the metered addition,the reaction temperature is held at 50 to 60° C. until the isocyanatemass fraction as determined by titration is at the theoreticallycalculated 70 mol %.

The solution of the partly silanized polyisocyanate has a solids contentof 55.0% by weight.

Preparation Example B4 Preparation of a Partly Silanized Polyisocyanate(HDI with 100 mol % of IIa: Conversion c=30 mol %)

A three-neck glass flask equipped with a reflux condenser and athermometer is charged with 57.3 parts by weight of trimerizedhexamethylene diisocyanate (HDI) (Basonat HI 100 from BASF AG) and 88.0parts by weight of solvent naphtha. With reflux cooling, nitrogenblanketing, and stirring, 30.7 parts by weight ofbis[3-(trimethoxysilyl)-propyl]amine (IIa) (Dynasilan® 1124 fromDegussa) are metered in at a rate such that 50 to 60° C. are notexceeded. After the end of the metered addition, the reactiontemperature is held at 50 to 60° C. until the isocyanate mass fractionas determined by titration is at the theoretically calculated 70 mol %.

The solution of the partly silanized polyisocyanate has a solids contentof 63.0% by weight.

Preparation Example B5 Preparation of a Partly Silanized Polyisocyanate(HDI with 100 mol % of IIIa: Conversion c=70 mol %)

A three-neck glass flask equipped with a reflux condenser and athermometer is charged with 57.3 parts by weight of trimerizedhexamethylene diisocyanate (HDI) (Basonat HI 100 from BASF AG) and 88.0parts by weight of solvent naphtha. With reflux cooling, nitrogenblanketing, and stirring, 49.4 parts by weight ofN-[3-(trimethoxysilyl)-propyl]butylamine (IIIa) (Dynasilan® 1189 fromDegussa) are metered in at a rate such that 50 to 60° C. are notexceeded. After the end of the metered addition, the reactiontemperature is held at 50 to 60° C. until the isocyanate mass fractionas determined by titration is at the theoretically calculated 30 mol %.

The solution of the partly silanized polyisocyanate has a solids contentof 54.8% by weight.

Preparation Example B6 Preparation of a Partly Silanized Polyisocyanate(HDI with 70 mol % of IIIa and 30 mol % of IIa: Conversion c=70 mol %)

A three-neck glass flask equipped with a reflux condenser and athermometer is charged with 57.3 parts by weight of trimerizedhexamethylene diisocyanate (HDI) (Basonat HI 100 from BASF AG) and 69.7parts by weight of solvent naphtha. With reflux cooling, nitrogenblanketing, and stirring, a mixture of 34.6 parts by weight ofN-[3-(tri-methoxysilyl)propyl]butylamine (Dynasilan® 1189 from Degussa)(IIIa) and 21.5 parts by weight of bis[3-(trimethoxysilyl)propyl]amine(IIa) (Dynasilan® 1124 from Degussa) is metered in at a rate such that50 to 60° C. are not exceeded. After the end of the metered addition,the reaction temperature is held at 50 to 60° C. until the isocyanatemass fraction as determined by titration is at the theoreticallycalculated 30 mol %.

The solution of the partly silanized polyisocyanate has a solids contentof 61.9% by weight.

Preparation Example B7 Preparation of a Partly Silanized Polyisocyanate(HDI with 30 mol % of IIIa and 70 mol % of IIa: Conversion c=70 mol %)

A three-neck glass flask equipped with a reflux condenser and athermometer is charged with 57.3 parts by weight of trimerizedhexamethylene diisocyanate (HDI) (Basonat HI 100 from BASF AG) and 88.0parts by weight of solvent naphtha. With reflux cooling, nitrogenblanketing, and stirring, a mixture of 14.8 parts by weight ofN-[3-(tri-methoxysilyl)propyl]butylamine (Dynasilan® 1189 from Degussa)(IIIa) and 50.2 parts by weight of bis[3-(trimethoxysilyl)propyl]amine(IIa) (Dynasilan® 1124 from Degussa) is metered in at a rate such that50 to 60° C. are not exceeded. After the end of the metered addition,the reaction temperature is held at 50 to 60° C. until the isocyanatemass fraction as determined by titration is at the theoreticallycalculated 70 mol %.

The solution of the partly silanized polyisocyanate has a solids contentof 58.2% by weight.

Preparation of the Polyacrylate Polyol A

In a steel tank reactor equipped with monomer inlet, initiator inlet,thermometer, oil heating, and reflux condenser, 29.08 parts by weight ofa commercial aromatic solvent mixture (Solventnaphtha® from DHC SolventChemie GmbH) are heated to 140° C. Then a mixture a1 of 3.39 parts byweight of solvent naphtha and 2.24 parts by weight of tert-butylperoxy-2-ethylhexanoate is added with stirring, at a rate such that theaddition of the mixture a1 is concluded after 6.75 h. 15 min after thebeginning of the addition of the mixture a1, a mixture a2 consisting of4.97 parts by weight of styrene, 16.91 parts by weight of tert-butylacrylate, 19.89 parts by weight of 2-hydroxypropyl methacrylate, 7.45parts by weight of n-butyl methacrylate, and 0.58 part by weight ofacrylic acid is added at a rate such that the addition of the mixture a2is concluded after 6 h. After the addition of the mixture a1, thereaction mixture is held at 140° C. for a further 2 h and then cooled tobelow 100° C. Subsequently the reaction mixture is diluted additionallywith a mixture a3 of 3.70 parts by weight of 1-methoxyprop-2-yl acetate,3.06 parts by weight of butyl glycol acetate, and 6.36 parts by weightof butyl acetate 98/100.

The resulting solution of the polyacrylate polyol A has a solids contentof 52.4% (1 h, 130° C., forced-air oven), a viscosity of 3.6 dPas (ICIcone/plate viscometer, 23° C.), a hydroxyl number of 155 mg KOH/g, andan acid number of 10-13 mg KOH/g.

Formulation of the Coating Compositions

The coating compositions were formulated as follows:

Component 1, containing component A (polyol) and commercial additivesand catalyst and solvent, is combined shortly before application withcomponent 2, containing component B (modified polyisocyanate),

and the components are stirred together until a homogeneous mixture isformed.

Application takes place pneumatically at 2.5 bar in three spray passes.Thereafter the coating is flashed off at room temperature for 5 minutesand subsequently baked at 140° C. for 22 minutes.

Table 1 lists all of the coating compositions in terms of theproportions of the components:

TABLE 1 Formulation of inventive coating compositions Example B1 B2 B3B4 B5 B6 B7 Component B B1 B2 B3 B4 B5 B6 B7 Parts by weight of 45.045.0 45.0 45.0 45.0 45.0 45.0 polyacrylate polyol A of example Parts byweight of 52.0 47.2 48.3 43.7 144.9 133.0 153.0 component B Parts byweight of 2.1 2.2 2.3 2.4 6.9 7.2 7.8 catalyst¹ (Nacure 4167, KingIndustries) non-volatile fraction 25% Parts by weight of BYK 0.2 0.2 0.20.2 0.2 0.2 0.2 301 (flow control agent, Byk Chemie) Parts by weight of0.9 0.9 0.9 0.9 0.9 0.9 0.9 Tinuvin 384.2 (Ciba) Parts by weight of 0.80.8 0.8 0.8 0.8 0.8 0.8 Tinuvin 292 (Ciba) Parts by weight of 20.0 20.020.0 20.0 20.0 20.0 20.0 Solventnaphtha (DHC Solvent Chemie GmbH)Equivalent ratio of free 1.00:1.00 1.00:1.00 1.00:1.00 1.00:1.001.00:1.00 1.00:1.00 1.00:1.00 isocyanate groups in component B tohydroxyl groups in polyacrylate polyol A Si content in % by 1.5 1.8 2.52.9 3.9 4.5 5.9 mass²) ¹catalyst based on amine-blocked phosphoric acidpartial ester ²)Si content calculated from the amounts of (IIa)/(IIIa)used, based on the solids content of the coating compositions

The scratchproofing of the surfaces of the resultant coatings was testedby means of the Crockmeter test (in general in accordance with EN ISO105-X12, with 10 double rubs and an applied force of 9 N, using 9 μmabrasive paper (3M 281Q, using Wetordry™ Production™), with subsequentdetermination of the residual gloss at 20° using a commerciallycustomary gloss meter), and by means of the hammer test (10 or 100double rubs with steel wool (RAKSO®00(fine)) with an applied weight of 1kg, implemented with a hammer. Subsequently, again, the residual glossat 20° is determined with a commercially customary gloss meter) and theweathering stability is investigated by means of the CAM180 test (to DINEN ISO 11341 February 98 and DIN EN ISO 4892-2 November 00). The resultsare listed in Table 2.

TABLE 2 Properties of the clearcoat films produced with the inventivecoating compositions Example B1 B2 B3 B4 B5 B6 B7 Crockmeter test 41 5358 63 75 88 95 (residual gloss in %) Hammer test 10 DR 38 49 60 64 79 8893 (residual gloss in %) Hammer test 100 DR 0 1 18 28 65 81 92 (residualgloss in %) Gloss 82 85 85 85 86 86 86 CAM 180 test (h) 5500 5250 50004500 5250 5000 4000 until appearance of cracks

Table 2 shows the properties of the coatings of examples B1 to B7,prepared from the inventive coating compositions comprising anisocyanurate adduct B originating from the reaction of the HDIisocyanurate with, in each case, a mixture of one component IIa and onecomponent IIIa (examples B2, B3, B6 and B7), in comparison to coatingcompositions comprising an isocyanurate adduct B originating from thereaction with the HDI isocyanurate, referred to as HDI for short below,and exclusively one component IIa (example B4) or IIIa (examples B1 andB5).

With a conversion of the isocyanate groups of the HDI of 30 mol %, B1(containing only structural units III) as against B4 (containing onlystructural units II), exhibits a much longer time in the CAM180 testuntil cracks appear. Correspondingly, for a conversion of the isocyanategroups of the HDI of 70 mol %, example B5 (containing only structuralunits III) as against B7 (containing 70 mol % of structural units II)exhibits a significantly longer time in the CAM180 test until cracksappear. The situation with the scratchproofing is the inverse of theweathering resistance: with a conversion of the isocyanate groups of theHDI of 30 mol %, B1 (containing only structural units III) as against B4(containing only structural units II), exhibits a much weakerscratchproofing in the various scratch tests. Correspondingly, with aconversion of the isocyanate groups of the HDI of 70 mol %, example B5(containing only structural units III) as against B7 (containing 70 mol% of structural units II) exhibits a significantly weakerscratchproofing in the various scratch tests. Since the relativefraction of the structure II hence shows itself to be responsible forthe scratchproofing, and the fraction of the structure III for theweathering resistance, a careful blending of both siloxane amines IIaand IIIa allows a fine-tuned balance to be struck between weatheringtime and scratchproofing. By way of example, B1 and B4 may be contrastedwith B2 and B3 in the group with 30 mol % conversion of the isocyanatefunctions. B1 achieves high weathering values, but the scratchproofingis moderate. B4 has good scratchproofing values, but is weaker inweathering. Both examples B2 and B3 have better scratchproofing than B1and better weathering times than B4.

Similar comments apply to B5 contrasted with B6 and B7 in the group with70 mol % conversion of isocyanate, although here both scratchproofingand weathering resistance are influenced more strongly, as a result ofthe high relative fraction of the siloxane functions. In addition it isclear that, with a high conversion of the isocyanate functions, therelative fraction of the structure III influences the weatheringresistance significantly more strongly than structure II influences thescratchproofing, as can easily be seen from comparing the values of B6and B7. In general, the scratchproofing value correlates with theconversion of the isocyanate groups with the compounds II and III, andin this context a higher conversion of the isocyanate groups is alsonecessary for the attainment of very high scratchproofing.

Comparative Examples 1 to 7

Examples 1 to 7 were repeated, albeit with the sole difference that thistime, instead of the catalyst based on amine-blocked phosphoric acidpartial ester, the catalyst used was blocked para-toluenesulfonic acid.Table 3 lists all of the coating compositions of the comparativeexamples in terms of the proportions of the components:

TABLE 3 Formulation of coating compositions of the comparative examplesExample VB1 VB2 VB3 VB4 VB5 VB6 VB7 Component B B1 B2 B3 B4 B5 B6 B7Parts by weight of 45.0 45.0 45.0 45.0 45.0 45.0 45.0 polyacrylatepolyol A of example Parts by weight of 52.0 47.2 48.3 43.7 144.9 133.0153.0 component B Parts by weight of 1.1 1.1 1.2 1.2 3.5 3.6 3.9catalyst³ (Dynapol 1203, Degussa) non- volatile fraction 50% Parts byweight of BYK 0.2 0.2 0.2 0.2 0.2 0.2 0.2 301 (flow control agent, BykChemie) Parts by weight of 0.9 0.9 0.9 0.9 0.9 0.9 0.9 Tinuvin 384.2(Ciba) Parts by weight of 0.8 0.8 0.8 0.8 0.8 0.8 0.8 Tinuvin 292 (Ciba)Parts by weight of 20.0 20.0 20.0 20.0 20.0 20.0 20.0 Solventnaphtha(DHC Solvent Chemie GmbH) Equivalent ratio of free 1.00:1.00 1.00:1.001.00:1.00 1.00:1.00 1.00:1.00 1.00:1.00 1.00:1.00 isocyanate groups incomponent B to hydroxyl groups in polyacrylate polyol A Si content in %by 1.5 1.8 2.5 2.9 3.9 4.5 5.9 mass⁴) ³catalyst based on blockedp-toluenesulfonic acid ⁴)Si content calculated from the amounts of(IIa)/(IIIa) used, based on the solids content of the coatingcompositions

TABLE 4 Properties of the clearcoat films produced with the coatingcompositions of the comparative examples Example VB1 VB2 VB3 VB4 VB5 VB6VB7 Crockmeter test 14 6 7 13 35 56 78 (residual gloss in %) Hammer test10 DR 16 23 32 36 44 67 79 (residual gloss in %) Hammer test 100 DR 0 00 7 20 53 58 (residual gloss in %) Gloss 82 85 84 84 84 85 85

The comparison of inventive examples 1 to 7 with comparative examplesVB1 to VB7 shows that the inventive coatings of examples B1 to B7exhibit good scratch resistance after final curing at 140° C. for 20minutes, whereas the corresponding coatings of comparative examples VB1to VB7 all exhibit significantly poorer scratch resistance after finalcuring at 140° C. for 20 minutes. The coatings of comparative examplesVB1 to VB4 in particular, therefore, must be given a thermalaftertreatment following the cure, in order to obtain the good scratchresistance required in the field of OEM finishing; this, however, isvery costly and inconvenient and therefore impracticable. Without thisaftertreatment, the low scratch resistance of the coatings directlyafter thermal curing means that their handling properties are limited atbest, given the risk of damage. In addition, the polishability of theresulting coatings that is necessary for line refinishing is presentonly to a limited extent for the coatings of the comparative examples.

As the silane content goes up, the coatings of the invention, moreparticularly of examples B3 to B7, also exhibit better gloss than thecoatings of the corresponding comparative examples.

A further disadvantage affecting the coatings of comparative examplesVB1 to VB7 is that—owing to strong post-crosslinking of the coatingssubsequent to the thermal cure—the ultimate hardness of the resultingcoatings is very much more difficult to set, if indeed it can be set atall. This post-crosslinking increases as the degree of silanization goesup and as the proportion of difunctional silane (IIa) goes up. Generallyspeaking, post-crosslinking also leads to poor reproducibility ofproperties of the resulting coatings and to the risk of the appearanceof stress cracks in the coatings of the comparative examples.

1. A coating composition based on aprotic solvents, comprising: (a) atleast one hydroxyl-containing compound (A), (b) at least one compound(B) having free and/or blocked isocyanate groups, (c) at least onecatalyst (D) for the crosslinking of silane groups, where (i) one ormore constituents of the coating composition contain hydrolyzable silanegroups and (ii) the coating composition can be finally cured to acoating which has statistically distributed regions of an Si—O—Sinetwork, characterized in that (iii) the catalyst (D) or the catalysts(D) is or are phosphorus-containing and (iv) one or more constituents ofthe coating composition comprise between 2.5 and 97.5 mol %, based onthe entirety of structural units (II) and (III), of at least onestructural unit of the formula (II)—N(X—SiR″x(OR′)3−x)n(X′—SiR″y(OR′)3−y)m  (II) where R′=hydrogen, alkylor cycloalkyl, it being possible for the carbon chain to be interruptedby nonadjacent oxygen, sulfur or NRa groups, with Ra=alkyl, cycloalkyl,aryl or aralkyl, preferably R′=ethyl and/or methyl X,X′=linear and/orbranched alkylene or cycloalkylene radical having 1 to 20 carbon atoms,preferably X,X′=alkylene radical having 1 to 4 carbon atoms, R″=alkyl,cycloalkyl, aryl or aralkyl, it being possible for the carbon chain tobe interrupted by nonadjacent oxygen, sulfur or NRa groups, withRa=alkyl, cycloalkyl, aryl or aralkyl, preferably R″=alkyl radical, inparticular having 1 to 6 carbon atoms, n=0 to 2, m=0 to 2, m+n=2, andx,y=0 to 2, and between 2.5 and 97.5 mol %, based on the entirety ofstructural units (II) and (III), of at least one structural unit of theformula (III)—Z—(X—SiR″x(OR′)3−x)  (III), where Z=—NH—, —NR—, —O—, with R=alkyl,cycloalkyl, aryl or aralkyl, it being possible for the carbon chain tobe interrupted by nonadjacent oxygen, sulfur or NRa groups, withRa=alkyl, cycloalkyl, aryl or aralkyl, x=0 to 2, and X, R′, R″ have themeaning given in formula (II).
 2. The coating composition according toclaim 1, characterized in that the catalyst (D) is phosphorus- andnitrogen-containing.
 3. The coating composition according to claim 1,characterized in that the catalyst (D) or the catalysts (D) is or areselected from the group of substituted phosphonic diesters and/ordiphosphonic diesters, of substituted phosphoric monoesters and/orphosphoric diesters, preferably from the group consisting of acyclicphosphoric diesters and/or cyclic phosphoric diesters, and/or thecorresponding amine-blocked phosphoric esters.
 4. The coatingcomposition according to claim 2, characterized in that the catalyst (D)is blocked with a tertiary amine.
 5. The coating composition accordingto claim 1, characterized in that the catalyst (D) is selected from thegroup of amine-blocked phosphoric acid ethylhexyl partial esters andamine-blocked phosphoric acid phenyl partial esters, more particularlyamine-blocked bis(ethylhexyl) phosphate.
 6. The coating compositionaccording to claim 1, characterized in that one or more constituents ofthe coating composition have at least partly one or more, identical ordifferent structural units of the formula (I)—X—Si—R″_(x)G_(3-x)  (I) where G=identical or different hydrolyzablegroups, more particularly G=alkoxy group (O R′), X=organic radical, moreparticularly linear and/or branched alkylene or cycloalkylene radicalhaving 1 to 20 carbon atoms, very preferably X=alkylene radical having 1to 4 carbon atoms, R″=alkyl, cycloalkyl, aryl or aralkyl, it beingpossible for the carbon chain to be interrupted by nonadjacent oxygen,sulfur or NRa groups, with Ra=alkyl, cycloalkyl, aryl or aralkyl,preferably R″=alkyl radical, more particularly having 1 to 6 C atoms,x=0 to 2, preferably 0 to 1, more preferably x=0.
 7. The coatingcomposition according to claim 1, characterized in that one or moreconstituents of the coating composition contain between 5 and 95 mol %,more particularly between 10 and 90 mol %, more preferably between 20and 80 mol %, and especially between 30 and 70 mol %, based in each caseon the entirety of the structural units (II) and (III), of at least onestructural unit of the formula (II), and between 5 and 95 mol %, moreparticularly between 10 and 90 mol %, more preferably between 20 and 80mol %, and especially between 30 and 70 mol %, based in each case on theentirety of the structural units (II) and (III), of at least onestructural unit of the formula (III).
 8. The coating compositionaccording to claim 1, characterized in that the structural elements (II)and (III) are present in fractions of 2.5 to 97.5 mol %, preferably of 5to 95 mol %, more preferably between 10 and 90 mol %, in each case basedon the sum of the functional groups critical for crosslinking in thecoating composition, formed from the fractions of the hydroxyl andisocyanate groups and from the fractions of the structural elements (II)and (III).
 9. The coating composition according to claim 1,characterized in that the coating composition contains less than 6.5% bymass of Si of the structural units (I) and/or (II) and/or (III),preferably not more than 6.0% by mass of Si of the structural units (I)and/or (II) and/or (III), based in each case on the solids content ofthe coating composition, wherein the structural units (I) have theformula (I)—X—Si—R″_(x)G_(3-x)  (I) where G=identical or different hydrolyzablegroups, more particularly G=alkoxy group (O R′), X=organic radical, moreparticularly linear and/or branched alkylene or cycloalkylene radicalhaving 1 to 20 carbon atoms, very preferably X=alkylene radical having 1to 4 carbon atoms, R″=alkyl, cycloalkyl, aryl or aralkyl, it beingpossible for the carbon chain to be interrupted by nonadjacent oxygen,sulfur or NRa groups, with Ra=alkyl, cycloalkyl, aryl or aralkyl,preferably R″=alkyl radical, more particularly having 1 to 6 C atoms,x=0 to 2, preferably 0 to 1, more preferably x=0.
 10. The coatingcomposition according to claim 1, characterized in that thepolyisocyanate (B) comprises the structural units (I) or (II) or (III),wherein the structural units (I) have the formula (I)—X—Si—R″_(x)G_(3-x)  (I) where G=identical or different hydrolyzablegroups, more particularly G=alkoxy group (O R′), X=organic radical, moreparticularly linear and/or branched alkylene or cycloalkylene radicalhaving 1 to 20 carbon atoms, very preferably X=alkylene radical having 1to 4 carbon atoms, R″=alkyl, cycloalkyl, aryl or aralkyl, it beingpossible for the carbon chain to be interrupted by nonadjacent oxygen,sulfur or NRa groups, with Ra=alkyl, cycloalkyl, aryl or aralkyl,preferably R″=alkyl radical, more particularly having 1 to 6 C atoms,x=0 to 2, preferably 0 to 1, more preferably x=0.
 11. The coatingcomposition according to claim 10, characterized in that, in thepolyisocyanate (B), between 2.5 and 90 mol % of the isocyanate groups inthe core polyisocyanate structure have undergone reaction to structuralunits (II) and between 2.5 and 90 mol % of the isocyanate groups in thecore polyisocyanate structure have undergone reaction to structuralunits (III) and/or the total fraction of the isocyanate groups in thecore polyisocyanate structure that have undergone reaction to structuralunits (II) and/or (III) is between 5 and 95 mol %.
 12. The coatingcomposition according to claim 10, characterized in that the corepolyisocyanate structure is selected from the group of 1,6-hexamethylenediisocyanate, isophorone diisocyanate, and 4,4′-methylenedicyclohexyldiisocyanate, the biuret dimers of the aforementioned polyisocyanatesand/or the isocyanurate trimers of the aforementioned polyisocyanates.13. The coating composition according to claim 1, characterized in thatthe polyol (A) comprises at least one poly(meth)acrylate polyol.
 14. Amultistage coating method, characterized in that a pigmented basecoatfilm is applied to an uncoated or precoated substrate and thereafter afilm of the coating composition according to claim 1 is applied.
 15. Themultistage coating method according to claim 14, characterized in that,following the application of the pigmented basecoat film, the appliedbasecoat material is first dried at temperatures from room temperatureto 80° C. and, following the application of the coating compositionaccording to any one of claim 1, the system is cured at temperaturesfrom 30 to 200° C. for a time of 1 min up to 10 h.
 16. The methodaccording to claim 14, wherein the method is a method for automotive OEMfinishing and automotive refinish.
 17. The coating composition accordingto claim 1, wherein the coating composition is a clearcoat material forautomotive OEM finishing and automotive refinish.
 18. The coatingcomposition according to claim 1, wherein the coating composition is atransparent clearcoat material for coating transparent plasticssubstrates.